An image reading device such as an OCR (Optical Character Reader) or a scanner detects an end of a business form by using the fact that the background of the business form is black, detects four corner points of the business form, performs skew correction, extracts characteristic components, and thus obtains character recognition results and image data.
When four corner points of a business form are detected and image data of the business form is acquired by using the above-described technique, there is a problem that only image data in which the image of a protruding portion (for example, a tab portion) is missing can be obtained in a case where the business form is not rectangular.
Japanese Patent Application Laid-Open Publication No. 2010-171492 discloses a technique, “an image processing device which processes an image of a document read by a reading device, the image processing device including: a recognition unit which recognizes that the read image of the document is an image of a tabbed sheet in which a tab portion is provided to protrude at a predetermined position of a business form main part; a separation unit which separates the image of the tab portion from the image of the tabbed sheet in a case where the image of the tabbed sheet is recognized by the recognition unit; and a generation unit which generates a tab embedded image having the same image size as the image size of the business form main part by superimposing the image of the tab portion separated by the separation unit on the image of the business form main part of the tabbed sheet from which the image of the tab portion is separated.”